Reality: Purchasing tickets months ahead of time used to be the best way to get a lower fare, but that's not necessarily true now. In fact, you can often find decent fares a few weeks out, and there's an abundance of last-minute deals.

• Perception: There's a specific day and time of the week -- say, Tuesdays at 11 p.m. -- when airlines change fares.

Reality: Years ago, fares changed only once or twice a week. Now, though, airlines change fares up to three times a day. The lesson: Check fares often.

• Perception: It's impossible to find advertised sale fares.

Reality: The advertised fare doesn't mean every ticket costs that much. It often applies to an extremely limited number of seats for flights at off-peak times.

They are there -- you just have to be quick and consider alternate dates and times.

• Perception: If you already bought a ticket and the price drops, you're out of luck.

Reality: Several airlines, including United, will refund the difference or apply a credit to your account if the price drops after you bought your tickets.